linux-kernel - Re: [PATCH] preserve correct battery state through suspend/resume cycles

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Message-ID: <20061008184230.GC4033@ucw.cz>
Date:	Sun, 8 Oct 2006 18:42:31 +0000
From:	Pavel Machek <pavel@...e.cz>
To:	Stefan Seyfried <seife@...e.de>
Cc:	Jiri Kosina <jikos@...os.cz>, linux-acpi@...el.com,
	linux-kernel@...r.kernel.org, Andrew Morton <akpm@...l.org>,
	Len Brown <len.brown@...el.com>
Subject: Re: [PATCH] preserve correct battery state through suspend/resume cycles

Hi!

> > boot -> suspend -> (un)plug battery -> resume
> > 
> > The problem arises in both cases - i.e. suspend with battery plugged in, 
> > and resume with battery unplugged, or vice versa.
> > 
> > After resume, when the battery status has changed (plugged in -> unplegged 
> > or unplugged -> plugged in) during the time when the system was sleeping, 
> > the /proc/acpi/battery/*/* is wrong (showing the state before suspend, not 
> > the current state).
> 
> Is this also needed if you use "platform" method? Also with suspend-to-RAM?
> 
> > The following patch adds ->resume method to the ACPI battery handler, which
> > has the only aim - to check whether the battery state has changed during sleep, 
> > and if so, update the ACPI internal data structures, so that information 
> > published through /proc/acpi/battery/*/* is correct even after suspend/resume
> > cycle, during which the battery was removed/inserted.
> 
> Although it generally is a good idea to add suspend and resume methods to
> all ACPI drivers, it would be interesting to know if you still need this
> when using the correct method (platform) instead of the incorrect default
> method (shutdown).
> 
> echo "platform" > /sys/power/disk
> echo "disk" > /sys/power/state

Maybe we should change the default in 2.6.20 or so?

-- 
Thanks for all the (sleeping) penguins.
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